Country finally doing something about its sewage

Instituto Costarricense de Acueductos
y Alcantarillados photo
Photo shows untreated sewage flowing into the
Río Tárcoles.

After years of planning and even years of neglect, Costa Rica is about to begin a project to protect its rivers and the gulf of Nicoya. This is a major step that will affirm to tourists the country’s strong environmental stand.

Construction is scheduled to begin next month on a primary sewage treatment plant in the Los Tajos section of León XII, a district of the Municipalidad de Tibás north of the capital. There may be some last-minute glitches, but the contract already has been approved with ACCIÓN Agua, a well-known Spanish firm that specializes in such projects. The price for the treatment plant alone is $44 million.

Primary treatment removes about 50 percent of the suspended solids in sewage. A secondary treatment plant at the same site, planned for 2025 will remove 90 percent of the solids and allow the plant to handle a much higher flow of sewage.

Sewage is a dull subject for most residents, but the problem in Costa Rica has been substantial. Every Central Valley sewer eventually dumps into a local river, which then pours into the Río Grande de Tárcoles. That river with all of the metro area trash and sewage dumps into the gulf of Nicoya north of Jacó. The pollution jeopardizes tourism beaches and the marine life in and around the gulf.

The Instituto Costarricense de Acueductos y Alcantarillados, the national water and sewer company, said about 45 percent of the Central Valley population, about 600,000 persons, are hooked up to sewer lines that eventually run into rivers. The rest have septic tanks or other disposal systems that can pollute the groundwater.

Instituto Costarricense de Acueductos
y Alcantarillados photo
Photo shows youngsters playing in water next to a
rusted-out main sewer line.

Acueductos y Alcantarillados says it hopes to service a million persons by 2016 in the first stage of the project. A second stage will include Heredia Centro, Alajuela Centro and other communities near the Tárcoles.

The first stage also includes replacing or extending sewer lines. Many are in bad condition. Some 361 kilometers of sewer lines will be replaced or installed, said the institute. That is about 224 miles. The estimated cost of the first stage, including the treatment plant, is $270 million.

The Japanese development agency has put $130 million in trust for the project. There was a delay in getting the legislature to accept the grant, and Costa Rica nearly lost the money.

Finally in September, after a lengthy bidding process, ACCIÓN Agua won the contract. The firm has 30 months to design and build the treatment plant and 18 months to run it and teach Costa Ricans how to do so, according to the agreement.

At the first stage treatment plant, after the solids are removed, the system will inject oxygen into the flow of water and subject it to chemical and biological agents that will decompose harmful bacteria in the sewage, according to the company. The solids, including trash and plastic soda bottles, will be trucked to a landfill.

In a presentation to the legislature, executives from Acueductos y Alcantarillados said that the entire project in two stages will run from the Cerro de Ochomogo on the east to the cerros Coyote and Palomas between Escazú and Santa Ana on the west. The project encompasses San Rafael de Coronado, San Gerónimo de Moravia and San Juan de Tibás.

To the south the project will take in Aserrí, San Miguel and Higuito de Desamparados and the Cerro del Tapezco in Escazú.

All of San José centro would be included in phase one as will San Pedro and Curridabat. So will much of La Uruca, part of Alajuelita, San Miguel, San Antonio, Damas, San Rafael Abajo and Gravilias, all Desamparados, Guadalupe, San Francisco, Calle Blancos, Ipís and Purral in Goicoechea, San Vicente and Trinidad in Moravia and León XIII, Colima, San Juan, Cinco Esquinas and Anselmo Llorente in Tibás. The rest of the valley will have to await phase two.

The project would join the four separate main sewers in the valley. They are named after the rivers they parallel.

A 1.8-kilometer tunnel will take the sewage underground in Hatillo. Sewage in Pavas and Escazú will be pumped up to the treatment plant. The rest of the network relies on gravity. Acueductos y Alcantarillados proposes using tunneling devices that will avoid open trenches and the disruption of traffic.

Officials have talked about creating biogas from the sewage.

Not all sewage runs into the rivers. Many hotels and condo projects have put in their own small-scale package treatment plants.

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